1. Field of the Invention
The present invention relates to a white standard paint with improvement of reflectivity characteristics for ultraviolet (hereinafter referred to as UV).
2. Description of Related Art
The white standard paint is used to define white color, for example, which is painted on the inner wall of an integrated sphere for spectrum transmittance and spectrum reflection meter to form a diffuse reflection characteristics film. This white standard paint comprises at least 3 components of barium sulfate, binder and solvent.
It is stated that the binder greatly contributes to the diffuse reflectivity characteristics and the know how around it is very important, since, the composition of the binder is not publicized by the paint manufacturers.
Nevertheless, the white standard paint on the market typically has not uniformity in diffuse reflectivity characteristics, it shows less diffuse reflectivity characteristics for UV than for the visible range. So far the market has a need for white standard paint with improved diffuse reflectivity characteristics.
Further, there are several problems that adhesion to the substrate on which the white standard paint is applied is weak, and proneness to cracks and the weather resistant against UV rays is poor.
The object of the present invention is to solve the above mentioned problems and to provide white standard paint that has good weather resistance and that improves reflectivity characteristics for UV as well as offering an improved adhesion to the substrate.
In accordance with one aspect of the invention, the white standard paint comprising barium sulfate, binder and solvent in which polyvinyl alcohol is included in said binder and said polyvinyl alcohol has a polymerization degree ranging from 900 to 1100 and a saponification degree ranging from 86 mol % to 90 mol % is provided.
The white standard paint in accordance with the first aspect of the invention shows improved weather resistance and reflectivity characteristics for UV range.
In accordance with another aspect of the invention, a white standard paint in which a mixture ratio of said binder and said barium sulfate is ranging from 0.5 wt. % to 6 wt. %, is provided.
The white standard paint in accordance with the second aspect shows the improved adhesion to the substrate without reducing the diffuse reflection characteristics.
In accordance with a third aspect of the invention, a white standard paint in which said barium sulfate has a purity degree of 99.9% and above is provided.
In accordance with other aspect of the invention, a white standard paint in which the paint further comprising distilled water and said solvent is ethanol, said barium sulfate has a purity degree of 99.9% and above, as well as a mixture ratio of 43.3 wt. %, a mixture ratio of said polyvinyl alcohol is 2.7 wt. %, a mixture ratio of said ethanol is 27.0 wt. % and said mixture ratio of said distilled water is residual, is provided.
In accordance with still other aspect of the invention, a white standard paint in which the paint further comprising distilled water and said solvent is ethanol, said barium sulfate has a purity degree of 99.9% and above, as well as a mixture ratio of 44.7 wt. %, a mixture ratio of said polyvinyl alcohol is 1.3 wt. %, a mixture ratio of said ethanol is 27.0 wt. % and said mixture ratio of said distilled water is residual, is provided.